JP6923392B2 - Ophthalmic equipment - Google Patents

Description

The present invention relates to an ophthalmic apparatus.

As an ophthalmic device for photographing the eye to be inspected, there are a device using optical coherence tomography (hereinafter, OCT), a fundus camera, a scanning laser optical probe (hereinafter, SLO), a slit lamp, and the like. .. Among them, OCT that forms an image showing the surface morphology and the internal morphology of the target eye by using a light beam from a laser light source or the like is attracting attention. Since OCT does not have the invasiveness to the human body like X-ray CT, it is expected to be applied especially in the medical field and the biology field. For example, in the field of ophthalmology, a device for forming an image of the anterior segment of the eye to be inspected and measuring the intraocular distance has been put into practical use.

In such an ophthalmic apparatus, tracking is an important technique for acquiring a high-definition image and measuring with high accuracy regardless of the eye movement of the eye to be inspected. Tracking is to move the device optical system according to the eye movement of the eye to be inspected. When tracking, alignment and focusing are performed in advance. Tracking is a function of maintaining a suitable positional relationship in which alignment and focus are achieved by making the position of the optical system of the device follow the movement of the eyeball. Various techniques related to such tracking have been proposed.

For example, in Patent Document 1, a fundus camera is used to acquire a base image and a target image of the fundus, and the base image and the target image are subjected to phase-limited correlation processing to obtain a minute amount of misalignment. An ophthalmologic apparatus that performs tracking control based on the amount of misalignment is disclosed.

Further, for example, in Patent Document 2, tracking of the anterior segment of the eye is started to adjust the focus of the SLO, and then tracking of the fundus is started to adjust the coherence gate, thereby shortening the time required for the adjustment. The method is disclosed.

Japanese Unexamined Patent Publication No. 2015-043898 Japanese Unexamined Patent Publication No. 2017-080561

When measuring or photographing the anterior segment of the eye to be inspected, an anterior segment image is acquired and tracking control is performed using the acquired anterior segment image. However, since the non-moving eyelids, eyelashes, and the like are depicted in the anterior segment image in addition to the pupil region that moves due to eye movement, the amount of misalignment cannot be determined by using phase-limited correlation processing. Therefore, with the conventional ophthalmic apparatus, it is possible to perform highly accurate tracking on the fundus of the eye to be inspected, but it is not possible to perform tracking on the anterior segment of the eye.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for suitably tracking according to a measurement site.

In the first aspect of the embodiment, an optical system for collecting data on the anterior segment or fundus of the eye to be inspected, an imaging unit for photographing the anterior segment or fundus, and the eye to be inspected and the optical system are provided. The eye to be inspected and the optical system based on a moving mechanism that moves relatively and an anterior segment image obtained by the imaging unit when the optical system is in the anterior segment mode for collecting data of the anterior segment. The movement mechanism is controlled so as to maintain the positional relationship of the eye, and the positional relationship is maintained based on the fundus image obtained by the imaging unit when the optical system is in the fundus mode for collecting the data of the fundus. It is an ophthalmologic apparatus including a control unit that controls the movement mechanism.

In addition, the second aspect of the embodiment includes an analysis unit that identifies a characteristic region in the anterior segment image in the first aspect, and in the anterior segment mode, the control unit is in the anterior segment image. The moving mechanism may be controlled based on the displacement of the feature region with respect to the reference position.

Further, in the third aspect of the embodiment, in the first aspect, a bright spot projection system that projects a bright spot onto the eye to be inspected and a bright spot based on the bright spot in the anterior eye portion image acquired by the photographing unit. In the anterior segment mode, which includes an analysis unit that identifies a point image, the control unit controls the movement mechanism based on the displacement of the bright spot image with respect to a reference position in the anterior segment image. May be good.

Further, in the fourth aspect of the embodiment, in the first aspect, the photographing unit includes two or more optometry cameras that photograph the anterior eye portion from different directions substantially at the same time, and the photographing unit substantially. Including an analysis unit that obtains a three-dimensional position of the eye to be inspected by analyzing two or more anterior segment images obtained at the same time, the control unit corresponds to the eye to be inspected in the anterior segment mode. The movement mechanism may be controlled based on the displacement of the three-dimensional position with respect to the reference position to move the eye to be inspected and the optical system three-dimensionally relative to each other.

Further, in the fifth aspect of the embodiment, in any of the second to fourth aspects, the photographing unit acquires the first image and the second image at different timings from each other, and the partial image in the second image. The first rotational movement amount calculation unit that calculates the first rotational movement amount between the first image and the corresponding partial image corresponding to the partial image in the first image, and the corresponding partial image based on the first rotational movement amount. Phase limitation with respect to the first alignment processing unit that aligns the image and the partial image in the rotational direction, and the corresponding partial image and the partial image that have been aligned by the first alignment processing unit. The control unit includes a first translation amount calculation unit that calculates a first translation amount between the corresponding partial image and the partial image by performing correlation processing, and in the anterior segment mode. Determines whether or not the positional relationship can be maintained based on the displacement, and when it is determined that the positional relationship cannot be maintained, moves the moving mechanism based on the first translation amount. You may control it.

Further, in the sixth aspect of the embodiment, in the fifth aspect, the first rotation movement amount calculation unit performs the phase-limited correlation processing on the corresponding partial image and the partial image to perform the first rotation movement amount. May be calculated.

Further, in the seventh aspect of the embodiment, in any of the second to sixth aspects, the photographing unit acquires the third image and the fourth image of the fundus of the eye to be inspected at different timings, and the image is described. A second rotation movement amount calculation unit that calculates a second rotation movement amount between the third image and the fourth image, and a rotation between the three images and the four images based on the second rotation movement amount. The second alignment processing unit that aligns the directions, and the third image and the fourth image that have been aligned by the second alignment processing unit are subjected to phase-limited correlation processing to perform the phase-limited correlation processing. A second translation amount calculation unit for calculating a second translation amount between the third image and the fourth image is included, and in the fundus mode, the control unit uses the second translation amount. The movement mechanism may be controlled based on the above.

Further, in the eighth aspect of the embodiment, in the seventh aspect, the analysis unit identifies the feature regions in the third image and the fourth image acquired by the photographing unit, and the control unit uses the control unit. It is determined whether or not the positional relationship can be maintained based on the two-rotational movement amount and the second parallel movement amount, and when it is determined that the positional relationship cannot be maintained, the third image and the said The movement mechanism may be controlled based on the displacement of the feature region in the fourth image.

Further, in the ninth aspect of the embodiment, an optical system for collecting data of a plurality of parts of the eye to be inspected, an imaging unit for photographing any of the plurality of parts, and the eye to be inspected and the optical system are provided. The positional relationship between the eye to be inspected and the optical system is maintained based on the image of the collection site according to the moving mechanism that moves relatively and the data collection site by the optical system obtained by the imaging unit. It is an ophthalmic apparatus including a control unit for controlling the movement mechanism.

In addition, it is possible to arbitrarily combine the configurations according to the above-mentioned plurality of aspects.

According to the present invention, it is possible to provide a technique for suitably tracking according to a measurement site.

It is the schematic which shows an example of the structure of the optical system of the ophthalmic apparatus which concerns on embodiment. It is the schematic which shows an example of the structure of the optical system of the ophthalmic apparatus which concerns on embodiment. It is the schematic which shows an example of the structure of the processing system of the ophthalmic apparatus which concerns on embodiment. It is the schematic which shows an example of the structure of the processing system of the ophthalmic apparatus which concerns on embodiment. It is the schematic for demonstrating the operation of the ophthalmic apparatus which concerns on embodiment. It is the schematic which shows an example of the structure of the processing system of the ophthalmic apparatus which concerns on embodiment. It is the schematic which shows an example of the structure of the processing system of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment. It is a flow chart of the operation example of the ophthalmic apparatus which concerns on embodiment.

An example of an embodiment of the ophthalmic apparatus according to the present invention will be described in detail with reference to the drawings. It should be noted that the description contents of the documents cited in this specification and arbitrary known techniques can be incorporated into the following embodiments.

The ophthalmic apparatus according to the embodiment is a measuring apparatus having at least a function of executing OCT and capable of acquiring information about the object to be measured by executing OCT on the object to be measured. Hereinafter, the case where the ophthalmic apparatus according to the embodiment images the living eye by performing OCT on the living eye as the object to be measured will be described, but the embodiment is not limited to this. For example, the ophthalmic apparatus according to the embodiment may be capable of measuring the intraocular distance of the living eye such as the axial length by performing OCT on the living eye.

The ophthalmic apparatus according to the embodiment is an ophthalmic apparatus that combines a Fourier domain OCT and a fundus camera. This ophthalmic device has the ability to perform swept source OCT, but embodiments are not limited to this. For example, the type of OCT is not limited to swept source OCT, and may be spectral domain OCT or the like. The swept source OCT divides the light from the wavelength sweep type (wavelength scanning type) light source into the measurement light and the reference light, and causes the return light of the measurement light passing through the object to be measured to interfere with the reference light to generate interference light. Then, this interference light is detected by a balanced photodiode or the like, and the detection data collected in response to the sweeping of the wavelength and the scanning of the measurement light is subjected to Fourier transform or the like to form an image. Spectral domain OCT divides the light from the low coherence light source into measurement light and reference light, and causes the return light of the measurement light that has passed through the object to be measured to interfere with the reference light to generate interference light. This is a method in which the spectral distribution is detected by a spectroscope and the detected spectral distribution is subjected to Fourier transform or the like to form an image.

The ophthalmic apparatus according to the embodiment is provided with a scanning laser ophthalmoscope (SLO), a slit lamp microscope, an anterior ocular segment imaging camera, a surgical microscope, a photocoagulation apparatus, and the like, instead of the fundus camera. May be good. In this specification, the measurement by OCT is collectively referred to as "OCT measurement", the image acquired by OCT is collectively referred to as an OCT image, the optical path of measurement light is referred to as "measurement optical path", and the optical path of reference light is referred to as "reference". Sometimes referred to as "optical path".

[composition]
As shown in FIG. 1, the ophthalmic apparatus 1 according to the embodiment includes a fundus camera unit 2, an OCT unit 100, and an arithmetic control unit 200. The fundus camera unit 2 has an optical system substantially similar to that of a conventional fundus camera. The OCT unit 100 is provided with an optical system for executing OCT. The arithmetic control unit 200 includes a processor that executes various arithmetic processes, control processes, and the like.

In the present specification, the "processor" is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), a programmable logic device (for example, a SPLD (Simple Program) It means a processing circuit including Programmable Logic Device), FPGA (Field Programmable Gate Array), and the like. The processor realizes the function according to the embodiment by reading and executing a program stored in a storage circuit or a storage device, for example.

[Fundus camera unit]
The fundus camera unit 2 is provided with an optical system for acquiring a two-dimensional image (fundus image) showing the surface morphology of the fundus Ef of the eye E to be inspected. The fundus image includes an observation image, a photographed image, and the like. The observation image is, for example, a monochrome moving image formed at a predetermined frame rate using near-infrared light. The captured image may be, for example, a color image obtained by flashing visible light, or a monochrome still image using near-infrared light or visible light as illumination light. The fundus camera unit 2 may be configured to be capable of acquiring images other than these, such as a fluorescein fluorescence image, an indocyanine green fluorescence image, and a spontaneous fluorescence image.

The fundus camera unit 2 is provided with a chin rest and a forehead pad for supporting the face of the subject. Further, the fundus camera unit 2 is provided with an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the fundus Ef with illumination light. The photographing optical system 30 guides the fundus reflected light of this illumination light to an image pickup device (CCD image sensor (sometimes simply referred to as CCD) 35, 38). Further, the photographing optical system 30 guides the measurement light from the OCT unit 100 to the eye E to be inspected, and guides the measurement light passing through the eye E to be inspected to the OCT unit 100.

The observation light source 11 of the illumination optical system 10 is composed of, for example, a halogen lamp or an LED (Light Emitting Diode). The light output from the observation light source 11 (observation illumination light) is reflected by the reflection mirror 12 having a curved reflecting surface, passes through the condenser lens 13, passes through the visible cut filter 14, and becomes near-infrared light. Become. Further, the observation illumination light is once focused in the vicinity of the photographing light source 15, reflected by the mirror 16, and passes through the relay lenses 17, 18, the diaphragm 19, and the relay lens 20. Then, the observation illumination light is reflected at the peripheral portion of the perforated mirror 21 (the region around the perforated portion), passes through the dichroic mirror 46, is refracted by the objective lens 22, and illuminates the fundus Ef.

The fundus reflected light of the observation illumination light is refracted by the objective lens 22, passes through the dichroic mirror 46, passes through the hole formed in the central region of the perforated mirror 21, passes through the dichroic mirror 55, and is focused for photographing. It is reflected by the mirror 32 via the lens 31. Further, the reflected light from the fundus of the eye passes through the half mirror 33A, is reflected by the dichroic mirror 33, and is imaged on the light receiving surface of the CCD image sensor 35 by the condenser lens 34. The CCD image sensor 35 detects the fundus reflected light at a predetermined frame rate, for example. An image (observation image) based on the fundus reflected light detected by the CCD image sensor 35 is displayed on the display device 3. When the photographing optical system 30 is focused on the anterior segment of the eye, the reflected light of the observation illumination light from the anterior segment of the eye is detected by the CCD image sensor 35, and the observation image of the anterior segment of the eye based on the reflected light. Is displayed on the display device 3.

The photographing light source 15 is composed of, for example, a xenon lamp or an LED. The light output from the photographing light source 15 (photographing illumination light) is applied to the fundus Ef through the same path as the observation illumination light. The fundus reflected light of the photographing illumination light is guided to the dichroic mirror 33 through the same path as that of the observation illumination light, passes through the dichroic mirror 33, is reflected by the mirror 36, and is reflected by the condensing lens 37 of the CCD image sensor 38. An image is formed on the light receiving surface. An image (captured image) based on the fundus reflected light detected by the CCD image sensor 38 is displayed on the display device 3. The display device 3 for displaying the observed image and the display device 3 for displaying the captured image may be the same or different. Further, when the eye E to be inspected is illuminated with infrared light and the same imaging is performed, an infrared captured image is displayed. It is also possible to use an LED as a photographing light source. When the photographing optical system 30 is focused on the anterior segment of the eye, the reflected light of the observation illumination light from the anterior segment of the eye is detected by the CCD image sensor 38, and an image of the anterior segment of the eye based on the reflected light ( The captured image) is displayed on the display device 3.

The LCD (Liquid Crystal Display) 39 displays a fixation target and a visual acuity measurement target. The fixation target is a target for fixing the eye E to be inspected, and is used at the time of fundus photography, OCT measurement, and the like.

A part of the light output from the LCD 39 is reflected by the half mirror 33A, reflected by the mirror 32, passes through the photographing focusing lens 31 and the dichroic mirror 55, and passes through the hole portion of the perforated mirror 21. The light that has passed through the hole of the perforated mirror 21 passes through the dichroic mirror 46, is refracted by the objective lens 22, and is irradiated to the fundus Ef. By changing the display position of the fixation target on the screen of the LCD 39, the fixation position of the eye E to be inspected can be changed.

Further, the fundus camera unit 2 is provided with an alignment optical system 50 and a focus optical system 60 as in the conventional fundus camera. The alignment optical system 50 generates an optotype (alignment optotype) for aligning the device optical system with respect to the eye E to be inspected. The focus optical system 60 generates an optotype (split optotype) for focusing on the eye E to be inspected.

The light (alignment light) output from the LED 51 of the alignment optical system 50 is reflected by the dichroic mirror 55 via the diaphragms 52 and 53 and the relay lens 54, and passes through the hole portion of the perforated mirror 21. The light that has passed through the hole of the perforated mirror 21 passes through the dichroic mirror 46 and is irradiated to the cornea of the eye E to be inspected by the objective lens 22.

The corneal reflected light of the alignment light passes through the objective lens 22, the dichroic mirror 46, and the hole portion, and a part of the light passes through the dichroic mirror 55 and passes through the photographing focusing lens 31. The corneal reflex light that has passed through the photographing focusing lens 31 is reflected by the mirror 32, transmitted through the half mirror 33A, reflected by the dichroic mirror 33, and projected onto the light receiving surface of the CCD image sensor 35 by the condenser lens 34. The received image (alignment optotype) by the CCD image sensor 35 is displayed on the display device 3 together with the observed image. The user performs the alignment by performing the same operation as the conventional fundus camera. Further, the arithmetic control unit 200 may analyze the position of the alignment optotype and move the optical system to perform alignment (auto alignment function).

The focus optical system 60 can move along the optical path of the illumination optical system 10. The photographing focusing lens 31 can move along the optical path of the photographing optical system 30 in conjunction with the movement of the focusing optical system 60. The reflection rod 67 of the focus optical system 60 is removable with respect to the illumination optical path.

When adjusting the focus, the reflecting surface of the reflecting rod 67 is obliquely provided on the illumination light path. The light (focus light) output from the LED 61 of the focus optical system 60 passes through the relay lens 62, is separated into two luminous fluxes by the split optotype plate 63, and passes through the two-hole diaphragm 64. The light that has passed through the two-hole diaphragm 64 is reflected by the mirror 65, is once imaged on the reflecting surface of the reflecting rod 67 by the condenser lens 66, and is reflected. The light reflected by the reflecting surface of the reflecting rod 67 passes through the relay lens 20, is reflected by the perforated mirror 21, passes through the dichroic mirror 46, is refracted by the objective lens 22, and is received as a pair of split optotypes. The eye examination E is irradiated.

The pair of split target lights that have passed through the pupil of the eye E to be inspected reach the fundus Ef of the eye E to be inspected. The fundus reflected light of the pair of split target lights passes through the pupil and is detected by the CCD image sensor 35 through the same path as the fundus reflected light flux of the illumination light. The received image (a pair of split optotype images) received by the CCD image sensor 35 is displayed on the display device 3 together with the observed image. The arithmetic control unit 200 analyzes the positions of the pair of split optotype images and moves the focus optical system 60 to perform focusing (autofocus function), as in the conventional case. By moving the photographing focusing lens 31 in conjunction with the movement of the focus optical system 60, the fundus image is formed on the imaging surface of the CCD image sensor 35. Further, focusing may be performed manually (by operating the operation unit 240B described later) while visually recognizing the pair of split optotype images.

The reflection rod 67 is inserted at a position on the illumination optical path that is optically substantially coupled to the fundus Ef of the eye E to be inspected. The position of the reflecting surface of the reflecting rod 67 inserted in the optical path of the illumination optical system 10 is a position substantially conjugate with the split optotype 63. As described above, the focus target light is separated into two by the action of the two-hole diaphragm 64 and the like. When the fundus Ef and the reflecting surface of the reflecting rod 67 are not conjugated, the pair of split optotype images acquired by the CCD image sensor 35 are displayed on the display device 3 separately in the left-right direction, for example. .. When the fundus Ef and the reflecting surface of the reflecting rod 67 are substantially conjugated, the pair of split optotype images acquired by the CCD image sensor 35 are displayed on the display device 3 so as to coincide with each other in the vertical direction, for example. When the focus optical system 60 is moved along the illumination optical path so that the fundus Ef and the split optotype 63 are always optically coupled, the photographing focusing lens 31 moves along the photographing optical axis in conjunction with this. Moving. When the fundus Ef and the split optotype 63 are not conjugated, the pair of split optotypes are separated into two, so that the pair of split optotypes coincide with each other in the vertical direction. The position of the photographing focusing lens 31 can be obtained by moving the lens 31. In this embodiment, the case where a pair of split optotypes is acquired has been described, but it may be three or more split optotypes.

The dichroic mirror 46 branches the optical path for OCT from the optical path for observation / photographing. The dichroic mirror 46 reflects light in the wavelength band used for OCT and transmits light for observation / photographing. The optical path for OCT is provided with a collimator lens unit 40, an optical path length changing unit 41, an optical scanner 42, an OCT focusing lens 43, a mirror 44, and a relay lens 45 in order from the OCT unit 100 side. Has been done.

The collimator lens unit 40 includes a collimator lens. The collimator lens unit 40 is optically connected to the OCT unit 100 by an optical fiber. The collimator lens of the collimator lens unit 40 is arranged at a position facing the exit end of the optical fiber. The collimator lens unit 40 converts the measurement light LS (described later) emitted from the emission end of the optical fiber into a parallel light flux, and collects the return light of the measurement light from the eye E to be examined at the emission end.

The optical path length changing unit 41 is movable in the direction of the arrow shown in FIG. 1, and changes the optical path length of the optical path for OCT. This change in the optical path length is used for correcting the optical path length according to the axial length of the eye E to be inspected, adjusting the interference state, and the like. The optical path length changing unit 41 includes, for example, a corner cube and a mechanism for moving the corner cube.

The optical scanner 42 is arranged, for example, at a position substantially conjugate with the pupil of the eye E to be inspected. The optical scanner 42 changes the traveling direction of the light (measurement light LS) passing through the optical path for OCT. Thereby, the eye E to be inspected can be scanned with the measurement light LS. The optical scanner 42 includes, for example, a galvano mirror that scans the measurement light LS in the x direction, a galvano mirror that scans the measurement light LS in the y direction, and a mechanism that independently drives them. Thereby, the measurement light LS can be scanned in any direction on the xy plane.

The OCT focusing lens 43 can move along the optical path (optical axis of the interference optical system) of the measurement light LS.

The ophthalmic apparatus 1 is provided with a front lens 23 that can be arranged between the eye E to be inspected and the objective lens 22. The front lens 23 can be manually placed between the eye E to be inspected and the objective lens 22. The front lens 23 may be automatically arranged between the eye E to be inspected and the objective lens 22 under the control of the control unit 210 described later. When the anterior lens 23 is retracted from between the eye E to be inspected and the objective lens 22, the focal position of the measurement light is arranged at or near the fundus Ef of the eye to be inspected E, and OCT measurement is performed on the fundus Ef. be able to. When the anterior lens 23 is arranged between the eye to be inspected E and the objective lens 22, the focal position of the measurement light is moved from the fundus Ef and arranged in or near the anterior segment of the eye, with respect to the anterior segment. OCT measurement can be performed.

[OCT unit]
An example of the configuration of the OCT unit 100 is shown in FIG. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the eye E to be inspected. This optical system divides the light from the wavelength sweep type (wavelength scanning type) light source into the measurement light and the reference light, and causes the return light of the measurement light from the subject E to interfere with the reference light passing through the reference optical path. This is an interference optical system that generates interference light and detects this interference light. The detection result (detection signal) of the interference light by the interference optical system is an interference signal showing the spectrum of the interference light, and is sent to the arithmetic control unit 200.

The light source unit 101 is configured to include a wavelength sweep type (wavelength scanning type) light source capable of sweeping (scanning) the wavelength of emitted light, similarly to a general swept source type ophthalmic apparatus. The wavelength sweep type light source is configured to include a laser light source including a resonator. The light source unit 101 changes the output wavelength with time in a near-infrared wavelength band that is invisible to the human eye.

The light L0 output from the light source unit 101 is guided by the optical fiber 102 to the polarization controller 103, and its polarization state is adjusted. The polarization controller 103 adjusts the polarization state of the light L0 guided in the optical fiber 102 by, for example, applying stress from the outside to the looped optical fiber 102.

The light L0 whose polarization state is adjusted by the polarization controller 103 is guided by the optical fiber 104 to the fiber coupler 105 and divided into the measurement light LS and the reference light LR.

The reference light LR is guided by the optical fiber 110 to the collimator 111 to become a parallel luminous flux. The reference light LR that has become a parallel luminous flux is guided to the optical path length changing unit 114. The optical path length changing unit 114 is movable in the direction of the arrow shown in FIG. 2, and changes the optical path length of the reference light LR. This movement changes the length of the optical path of the reference light LR. This change in the optical path length is used for correcting the optical path length according to the axial length of the eye E to be inspected, adjusting the interference state, and the like. The optical path length changing unit 114 includes, for example, a corner cube and a moving mechanism for moving the corner cube. In this case, the corner cube of the optical path length changing portion 114 turns back the traveling direction of the reference light LR, which is converted into a parallel luminous flux by the collimator 111, in the opposite direction. The optical path of the reference light LR incident on the corner cube and the optical path of the reference light LR emitted from the corner cube are parallel.

In the configurations shown in FIGS. 1 and 2, the optical path length changing unit 41 for changing the length of the optical path (measurement optical path, measurement arm) of the measurement light LS and the optical path of the reference light LR (reference optical path, reference). Both of the optical path length changing portions 114 for changing the length of the arm) are provided. However, only one of the optical path length changing portions 41 and 114 may be provided. It is also possible to change the difference between the reference optical path length and the measured optical path length by using an optical member other than these.

The reference light LR that has passed through the optical path length changing unit 114 is converted from a parallel luminous flux to a focused luminous flux by the collimator 116 and is incident on the optical fiber 117.

An optical path length correction member may be arranged at least one of the reference optical path between the collimator 111 and the optical path length changing unit 114 and the reference optical path between the collimator 116 and the optical path length changing unit 114. The optical path length correction member acts as a delay means for matching the optical path length (optical distance) of the reference light LR with the optical path length of the measurement light LS.

The reference light LR incident on the optical fiber 117 is guided by the polarization controller 118 to adjust its polarization state. The polarization controller 118 has, for example, the same configuration as the polarization controller 103. The reference light LR whose polarization state is adjusted by the polarization controller 118 is guided to the attenuator 120 by the optical fiber 119, and the amount of light is adjusted under the control of the arithmetic control unit 200. The reference light LR whose light amount is adjusted by the attenuator 120 is guided to the fiber coupler 122 by the optical fiber 121.

On the other hand, the measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127 and is converted into a parallel luminous flux by the collimator lens unit 40. The measurement light LS converted into a parallel luminous flux is guided to the dichroic mirror 46 via the optical path length changing unit 41, the optical scanner 42, the OCT focusing lens 43, the mirror 44, and the relay lens 45. The measurement light LS guided to the dichroic mirror 46 is reflected by the dichroic mirror 46, refracted by the objective lens 22, and irradiated to the eye E to be inspected. The measurement light LS is scattered (including reflection) at various depth positions of the eye E to be inspected. The return light of the measurement light LS including such backscattered light travels in the same path as the outward path in the opposite direction, is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

The fiber coupler 122 generates interference light by synthesizing (interfering with) the measurement light LS incidented through the optical fiber 128 and the reference light LR incidented via the optical fiber 121. The fiber coupler 122 generates a pair of interference light LCs by branching the interference light between the measurement light LS and the reference light LR at a predetermined branching ratio (for example, 1: 1). The pair of interference light LCs emitted from the fiber coupler 122 are guided to the detector 125 by the optical fibers 123 and 124, respectively.

The detector 125 is, for example, a balanced photodiode (Balanced Photo Diode) that has a pair of photodetectors that detect each pair of interference light LCs and outputs the difference between the detection results by these. The detector 125 sends the detection result (interference signal) to the DAQ (Data Acquisition System) 130. A clock KC is supplied to the DAQ 130 from the light source unit 101. The clock KC is generated in the light source unit 101 in synchronization with the output timing of each wavelength swept (scanned) within a predetermined wavelength range by the wavelength sweep type light source. The light source unit 101 optically delays one of the two branched lights obtained by branching the light L0 of each output wavelength, and then sets the clock KC based on the result of detecting the combined light. Generate. The DATA 130 samples the detection result of the detector 125 based on the clock KC. The DAQ 130 sends the detection result of the sampled detector 125 to the arithmetic control unit 200. The arithmetic control unit 200 obtains a reflection intensity profile in each A line by, for example, performing a Fourier transform or the like on the spectral distribution based on the detection result obtained by the detector 125 for each series of wavelength scans (for each A line). Form. Further, the arithmetic control unit 200 forms image data by imaging the reflection intensity profile of each A line.

[Calculation control unit]
The configuration of the arithmetic control unit 200 will be described. The arithmetic control unit 200 analyzes the interference signal input from the detector 125 to form an OCT image of the eye E to be inspected. The arithmetic processing for forming the OCT image is the same as that of the conventional swept source type ophthalmic apparatus.

Further, the arithmetic control unit 200 controls each part of the fundus camera unit 2, the display device 3, and the OCT unit 100. For example, the arithmetic control unit 200 causes the display device 3 to display the OCT image of the eye E to be inspected.

The arithmetic control unit 200 includes, for example, a microprocessor, a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk drive, a communication interface, and the like, similarly to a conventional computer. A computer program for controlling the ophthalmic apparatus 1 is stored in a storage device such as a hard disk drive. The arithmetic control unit 200 may include various circuit boards, for example, circuit boards for forming OCT images. Further, the arithmetic control unit 200 may include an operation device (input device) such as a keyboard and a mouse, and a display device such as an LCD.

[Control system]
The configuration of the processing system of the ophthalmic apparatus 1 will be described with reference to FIGS. 3, 4, 6 and 7. In FIG. 3, some components of the ophthalmic apparatus 1 are omitted, and components particularly necessary for explaining this embodiment are selectively shown.

(Control unit)
The arithmetic control unit 200 includes a control unit 210, an image forming unit 220, and a data processing unit 230. The control unit 210 includes, for example, a microprocessor, RAM, ROM, a hard disk drive, a communication interface, and the like. The control unit 210 is provided with a main control unit 211 and a storage unit 212.

The function of the main control unit 211 is realized by, for example, a microprocessor. A computer program for controlling the ophthalmic apparatus is stored in the storage unit 212 in advance. This computer program includes various light source control programs, optical scanner control programs, various detector control programs, image formation programs, data processing programs, user interface programs, and the like. When the main control unit 211 operates according to such a computer program, the control unit 210 executes the control process.

(Main control unit)
The main control unit 211 performs the above-mentioned various controls. In particular, as shown in FIG. 3, the main control unit 211 controls the focusing drive units 31A and 43A of the fundus camera unit 2, the CCD image sensors 35 and 38, the LCD 39, the optical path length changing unit 41, and the optical scanner 42. .. Further, the main control unit 211 controls the optical system drive unit 1A. Further, the main control unit 211 controls the light source unit 101 of the OCT unit 100, the optical path length changing unit 114, the detector 125, the DAQ 130, and the like.

The focusing drive unit 31A receives control from the main control unit 211 and moves the photographing focusing lens 31 along the optical axis of the photographing optical system 30. The focusing drive unit 31A is provided with a holding member for holding the photographing focusing lens 31, an actuator for generating a driving force for moving the holding member, and a transmission mechanism for transmitting the driving force. The actuator is composed of, for example, a pulse motor. The transmission mechanism is composed of, for example, a combination of gears and a rack and pinion. As a result, the focusing drive unit 31A controlled by the main control unit 211 moves the photographing focusing lens 31, so that the focusing position of the photographing optical system 30 is changed. The focusing drive unit 31A may move the photographing focusing lens 31 along the optical axis of the photographing optical system 30 manually or by operating the operation unit 240B of the user.

The focusing drive unit 43A receives control from the main control unit 211 and moves the OCT focusing lens 43 along the optical axis (optical path of the measurement light) of the interference optical system in the OCT unit 100. The focusing drive unit 43A is provided with a holding member for holding the OCT focusing lens 43, an actuator for generating a driving force for moving the holding member, and a transmission mechanism for transmitting the driving force. The actuator is composed of, for example, a pulse motor. The transmission mechanism is composed of, for example, a combination of gears and a rack and pinion. As a result, the focusing drive unit 43A controlled by the main control unit 211 moves the OCT focusing lens 43, so that the focusing position of the measurement light is changed. The focusing drive unit 43A may move the OCT focusing lens 43 along the optical axis of the interference optical system by manual operation or operation with respect to the operation unit 240B by the user.

The main control unit 211 can control the exposure time (charge accumulation time), sensitivity, frame rate, etc. of the CCD image sensor 35. The main control unit 211 can control the exposure time, sensitivity, frame rate, etc. of the CCD image sensor 38.

The main control unit 211 can control the display of the fixation target and the visual acuity measurement target on the LCD 39. As a result, it is possible to switch the optotype presented to the eye E to be inspected and to change the type of optotype. Further, by changing the display position of the optotype on the LCD 39, it is possible to change the optotype presentation position with respect to the eye E to be inspected.

By controlling the optical path length changing unit 41, the main control unit 211 can relatively change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS. The main control unit 211 controls the optical path length changing unit 41 so that the target portion of the eye E to be inspected is drawn in a predetermined range within the frame of the OCT image. Specifically, the main control unit 211 controls the optical path length changing unit 41 so that the target portion of the eye E to be inspected is drawn at a predetermined z position (position in the depth direction) in the frame of the OCT image. Is possible.

By controlling the optical scanner 42, the main control unit 211 can change the scanning position of the measurement light LS in the fundus Ef of the eye E to be inspected or the anterior eye portion.

The optical system drive unit 1A three-dimensionally moves the optical system (optical system shown in FIGS. 1 and 2) provided in the ophthalmic apparatus 1. The optical system drive unit 1A moves the optical system under the control of the main control unit 211. This control is used in alignment and tracking. Tracking is to move the device optical system according to the movement of the eye E to be inspected. When tracking is performed, alignment and focusing are performed in advance. Tracking maintains a suitable positional relationship in which alignment and focus are achieved by moving the device optical system in real time according to the position and orientation of the eye E to be inspected based on an image obtained by capturing a moving image of the eye E to be inspected. It is a function.

By controlling the light source unit 101, the main control unit 211 can control switching between turning on and off the light L0, changing the amount of light of the light L0, and the like.

By controlling the optical path length changing unit 114, the main control unit 211 can relatively change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS. The main control unit 211 controls the optical path length changing unit 114 so that the target portion of the eye E to be inspected is drawn in a predetermined range within the frame of the OCT image. Specifically, the main control unit 211 can control the optical path length changing unit 114 so that the target portion of the eye E to be inspected is drawn at a predetermined z position in the frame of the OCT image. By controlling at least one of the optical path length changing units 41 and 114, the main control unit 211 can relatively change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS. Hereinafter, the main control unit 211 will be described as adjusting the optical path length difference between the measurement light LS and the reference light LR by controlling only the optical path length changing unit 114, but controls only the optical path length changing unit 41. Therefore, the optical path length difference between the reference light LR and the measurement light LS may be adjusted.

The main control unit 211 can control the exposure time (charge accumulation time), sensitivity, frame rate, etc. of the detector 125. Further, the main control unit 211 can control the DAQ 130.

The main control unit 211 can control the optical system drive unit 1A so as to maintain the positional relationship between the eye E to be inspected and the device optical system. In this embodiment, the main control unit 211 performs tracking control by a method corresponding to an imaging region (measurement region, data collection region). In particular, the main control unit 211 can control the optical system drive unit 1A based on the amount of misalignment obtained with high accuracy by the phase only correlation (POC) process. In particular, when the imaged portion is the fundus, the entire acquired fundus image moves with respect to the reference image (base image), so that the amount of misalignment can be obtained with high accuracy by phase-limited correlation processing. On the other hand, when the imaging region is the anterior segment, a part of the acquired anterior segment image does not move, so that the amount of misalignment cannot be obtained by applying the phase-limited correlation processing as it is.

For example, in the anterior segment image IMG shown in FIG. 5, since a predetermined region including a pupil region corresponding to the pupil of the eye E to be inspected moves, phase-limited correlation processing is applied to the partial image PIMG including the predetermined region. can do. However, the region AR1 containing the eyelashes and the region AR2 containing the lower eyelid do not move. Therefore, if the phase-limited correlation processing is applied to the anterior segment image IMG as it is, the amount of misalignment cannot be obtained with high accuracy.

Therefore, the main control unit 211 controls the optical system drive unit 1A so as to maintain the positional relationship between the eye E to be inspected and the optical system of the apparatus based on the image of the imaged portion according to the imaged portion. In this embodiment, the imaging site is the fundus or anterior segment of the eye. Therefore, when the front lens 23 is retracted from between the eye E to be inspected and the objective lens 22, the main control unit 211 performs tracking control in the fundus mode. When the front lens 23 is arranged between the eye E to be inspected and the objective lens 22, the main control unit 211 performs tracking control in the front eye mode.

In the fundus mode, the main control unit 211 performs tracking control based on the fundus image of the eye E to be inspected obtained by the photographing optical system 30. The fundus images are acquired as a base image and a target image at different timings from each other. The main control unit 211 refers to the base image which is the anterior segment image of the eye E to be inspected obtained in advance, and the displacement amount (position) of the target image which is the anterior segment image obtained after the acquisition of the base image. (Including the deviation direction) can be obtained, and tracking control can be performed based on the obtained displacement amount. The amount of misalignment of the target image with respect to the base image is obtained by phase-limited correlation processing. The main control unit 211 can control the optical system drive unit 1A based on the obtained amount of misalignment.

In the anterior segment mode, the main control unit 211 performs tracking control based on the anterior segment image of the eye E to be inspected obtained by the photographing optical system 30. The main control unit 211 performs tracking control so that, for example, the feature region in the anterior segment image is arranged at a reference position. That is, the main control unit 211 can obtain the amount of misalignment of the position of the feature region with respect to the reference position, and can control the optical system drive unit 1A so that the obtained amount of misalignment is cancelled. The reference position may be the position of the feature region in the anterior segment image acquired before the anterior segment image, or may be a predetermined position in the anterior segment image. The predetermined position includes a position corresponding to the optical axis of the objective lens 22, a center position of the anterior segment image, and the like.

(Memory)
The storage unit 212 stores various types of data. Examples of the data stored in the storage unit 212 include image data of an OCT image, image data of a fundus image and an anterior eye portion image, and eye information to be inspected. The eye test information includes information about the subject such as the patient ID and name, and information about the test eye such as left eye / right eye identification information. Further, the storage unit 212 stores data such as various programs and control information for operating the ophthalmic apparatus 1.

(Image forming part)
The image forming unit 220 forms image data of a tomographic image of the fundus Ef and the anterior segment of the eye based on the interference signal from the detector 125 (DAQ130). This process includes processing such as noise removal (noise reduction), filter processing, and FFT (Fast Fourier Transform). The image data acquired in this way is a data set including a group of image data formed by imaging the reflection intensity profile in a plurality of A lines (paths of each measurement light LS in the eye E to be inspected). be.

In order to improve the image quality, it is possible to superimpose (add and average) a plurality of data sets collected by repeating scanning with the same pattern a plurality of times.

Further, the image forming unit 220 can form an anterior segment image based on the detection result of the reflected light from the anterior segment of the eye E to be inspected by the CCD image 35 or the CCD image sensor 38.

The image forming unit 220 includes, for example, the circuit board described above. In this specification, "image data" and "image" based on the "image data" may be equated. In addition, the site of the eye E to be inspected and the image thereof may be equated.

(Data processing unit)
The data processing unit 230 performs various data processing (image processing) and analysis processing on the image formed by the image forming unit 220. For example, the data processing unit 230 executes correction processing such as image brightness correction and dispersion correction.

The data processing unit 230 can form volume data (voxel data) of the eye E to be inspected by executing known image processing such as interpolation processing for interpolating pixels between tomographic images. When displaying an image based on volume data, the data processing unit 230 performs rendering processing on the volume data to form a pseudo three-dimensional image when viewed from a specific line-of-sight direction.

The data processing unit 230 can align the fundus image (or the anterior segment image) with the OCT image. When the fundus image (or anterior segment image) and the OCT image are acquired in parallel, the fundus image (or anterior segment image) acquired at the same time (almost) because both optical systems are coaxial. ) And the OCT image can be aligned with respect to the optical axis of the photographing optical system 30. Further, regardless of the acquisition timing of the fundus image (or the anterior segment image) and the OCT image, at least a part of the corresponding image region of the fundus Ef (or the anterior segment image) of the OCT image is projected onto the xy plane. By aligning the frontal image obtained with the fundus image (or the anterior segment image), the OCT image and the fundus image (or the anterior segment image) can be aligned. This alignment method can be applied even when the optical system for acquiring a fundus image (or for acquiring an anterior segment image) and the optical system for OCT are not coaxial. Even if both optical systems are not coaxial, if the relative positional relationship between the two optical systems is known, the same alignment as in the case of coaxial is executed with reference to this relative positional relationship. It is possible.

As shown in FIG. 4, the data processing unit 230 is provided with an analysis unit 231, a rotational movement amount calculation unit 241, an alignment processing unit 242, and a translation movement amount calculation unit 243.

The analysis unit 231 performs an analysis process on the image obtained by the photographing optical system 30. The analysis process includes a process of specifying a feature area and a feature position in an image.

(Anterior segment mode)
In the anterior segment mode, the analysis unit 231 performs, for example, a process of specifying a feature region and a feature position in the anterior segment image.

For example, the analysis unit 231 can specify a predetermined region including a region corresponding to the pupil of the eye E to be inspected as a characteristic region in the anterior segment image. In the anterior segment mode, the main control unit 211 controls the optical system drive unit 1A based on the displacement of the feature region with respect to the reference position in the anterior segment image. As a result, when the imaging region is the anterior segment of the eye, tracking can be performed based on the position of the feature region. The characteristic region may be an iris region, a blood vessel, a diseased portion, or the like.

Further, for example, using the photographing optical system 30, an image of the anterior segment of the eye to be inspected E on which an optotype (bright spot) is projected from the alignment optical system 50 is acquired. The analysis unit 231 identifies a bright spot image based on the bright spot in the acquired anterior segment image. In the anterior segment mode, the main control unit 211 controls the optical system drive unit 1A based on the displacement of the bright spot image with respect to the reference position in the anterior segment image. As a result, when the imaging region is the anterior segment of the eye, tracking based on the position of the bright spot image can be performed.

Further, for example, the photographing optical system 30 may include two or more anterior segment cameras that photograph the anterior segment from different directions substantially simultaneously. At this time, the analysis unit 231 obtains the three-dimensional position of the eye E to be inspected by analyzing two or more anterior segment images obtained substantially simultaneously by the two or more anterior segment cameras. In the anterior segment mode, the main control unit 211 controls the optical system drive unit 1A based on the displacement of the three-dimensional position with respect to the reference position corresponding to the eye to be inspected, and makes the eye to be inspected E and the device optical system three-dimensional. Relative movement. As a result, when the imaging region is the anterior segment of the eye, tracking can be performed based on the three-dimensional position of the eye E to be inspected.

As will be described later, the analysis unit 231 can also specify a predetermined region including a region corresponding to the pupil in the anterior segment image. In this case, in the anterior segment mode, highly accurate tracking can be performed by using the phase-limited correlation processing described later based on the partial image including the predetermined region. That is, in the anterior segment mode as well, the main control unit 211 performs tracking control based on the anterior segment of the eye E to be inspected obtained by the photographing optical system 30 as in the fundus mode. The anterior segment image is acquired as a base image and a target image at different timings from each other.

As shown in FIG. 5, the analysis unit 231 identifies a partial image PIMG which is an image of a predetermined region from the target image IMG. The analysis unit 231 can identify the partial image PIMG in the target image IMG by analyzing the base image and the target image.

In the target image, the analysis unit 231 can specify an image in a region where the amount of movement with respect to the base image is equal to or greater than the first threshold value as a partial image. For example, the analysis unit 231 divides the target image into a plurality of regions, obtains the amount of movement of the target image with respect to the base image for each area, and uses an image of a region in which the obtained movement amount is equal to or greater than the first threshold value as a partial image. Identify. That is, the analysis unit 231 specifies an image of a region that moves with respect to the base image as a partial image in the target image.

Further, the analysis unit 231 identifies a region (for example, regions AR1 and AR2 in FIG. 5) in which the amount of movement with respect to the base image is equal to or less than the second threshold value in the target image, and obtains an image of the region excluding the region from the target image. It can be specified as a partial image. For example, the analysis unit 231 divides the target image into a plurality of regions, obtains the movement amount of the target image with respect to the base image for each region, identifies the region where the obtained movement amount is equal to or less than the second threshold value, and identifies the target image. The image of the area excluding the area specified from is specified as a partial image. That is, the analysis unit 231 specifies a region in the target image that does not move with respect to the base image, and identifies a region excluding the region from the target image as a partial image.

Further, the analysis unit 231 specified an image of a region (for example, regions AR1 and AR2 in FIG. 5) in which the eyelids (upper eyelid, lower eyelid) or eyelashes were drawn in the target image, and removed the region from the target image. It is possible to specify the image of the area as a partial image. For example, the analysis unit 231 specifies a region including a shape corresponding to an eyelid or eyelashes from the brightness information of each pixel in the target image, and identifies an image of a region excluding the region from the target image as a partial image.

Further, the analysis unit 231 can specify an image of a predetermined region in the target image as a partial image. The predetermined region may include a region corresponding to the pupil of the eye E to be inspected, and may be a region in which the upper eyelid, the lower eyelid, and the eyelashes of the eye to be inspected are not visualized. For example, the analysis unit 231 extracts a predetermined region from the target image and specifies the extracted image as a partial image. That is, the analysis unit 231 specifies an image in a region where the angle of view is narrowed from the target image as a partial image.

In the partial image specified as described above, the region corresponding to the pupil of the eye E to be inspected is drawn, and the upper eyelid, the lower eyelid, and the eyelashes of the eye E to be inspected are not drawn.

The analysis unit 231 may specify a partial image in the target image based on an image in a predetermined region in the base image. For example, the analysis unit 231 identifies a partial image in the target image from the image of the region corresponding to the pupil of the eye E to be inspected in the base image.

The analysis unit 231 identifies the corresponding partial image in the base image corresponding to the partial image specified as described above.

The data processing unit 230 obtains the amount of misalignment between the corresponding partial image in the base image and the partial image in the target image, and the control unit 210 (main control unit 211) obtains information corresponding to the obtained amount of misalignment. Output to. The amount of misalignment is the amount of rotational movement in the subpixel level rotation direction (rotational direction centered on the z-direction axis) of less than 1 pixel between the corresponding partial image and the partial image, the rotational movement direction, and the corresponding partial image. It includes the amount of translation in the xy plane at the sub-pixel level between the image and the partial image, the translation direction thereof, and the like.

Specifically, the data processing unit 230 calculates the rotational movement amount and the rotational movement direction between the corresponding partial image and the partial image at the sub-pixel level, and responds based on the calculated rotational movement amount and the rotational movement direction. Align the partial image and the partial image in the rotation direction. After that, the data processing unit 230 calculates the amount of translation and the direction of translation between the aligned partial image and the partial image at the sub-pixel level.

The rotational movement amount calculation unit 241 and the parallel movement amount calculation unit 243 determine the displacement (including the displacement amount and the displacement direction) of the partial image with respect to the corresponding partial image based on the corresponding partial image and the partial image as described above. Ask. The alignment processing unit 242 aligns the corresponding partial image with the partial image.

The rotational movement amount calculation unit 241 calculates the rotational movement amount and the rotational movement direction between the corresponding partial image and the partial image. The rotational movement amount calculation unit 241 can calculate the rotational movement amount and the rotational movement direction between the corresponding partial image and the partial image by performing phase-limited correlation processing on the corresponding partial image and the partial image. be.

(Fundus mode)
The data processing unit 230 obtains the amount of misalignment between the base image and the target image, and outputs information corresponding to the obtained amount of misalignment to the control unit 210 (main control unit 211). The amount of misalignment is the amount of rotational movement in the subpixel level rotation direction (rotational direction centered on the z-direction axis) of less than 1 pixel between the base image and the target image, the rotational movement direction, and the base image and the target. Includes the amount of translation in the xy plane at the sub-pixel level with the image and the direction of translation thereof.

Specifically, the data processing unit 230 calculates the rotational movement amount and the rotational movement direction between the base image and the target image at the sub-pixel level, and based on the calculated rotational movement amount and the rotational movement direction, the base image. Aligns the image with the target image in the direction of rotation. After that, the data processing unit 230 calculates the amount of translation and the direction of translation between the aligned base image and the target image at the sub-pixel level.

The rotational movement amount calculation unit 241 and the parallel movement amount calculation unit 243 obtain the displacement (including the displacement amount and the displacement direction) of the target image with respect to the base image based on the base image and the target image as described above. The alignment processing unit 242 aligns the base image and the target image.

The rotational movement amount calculation unit 241 calculates the rotational movement amount and the rotational movement direction between the base image and the target image. The rotational movement amount calculation unit 241 can calculate the rotational movement amount and the rotational movement direction between the base image and the target image by performing phase-limited correlation processing on the base image and the target image. Such a phase-limited correlation process is the same as the process disclosed in Japanese Patent Application Laid-Open No. 2015-043898 (Patent Document 1).

In the phase-limited correlation processing according to the embodiment, for example, the following phase-limited correlation function is used. Hereinafter, the case of the fundus mode will be mainly described, but it can be applied to the anterior segment mode by replacing the base image with the “corresponding partial image” and replacing the target image with the “partial image”.

_{First, let f (n 1} , n ₂ ) be a base image having an image size of N ₁ × N ₂ (N ₁ and N ₂ are positive integers), and g (n ₁ , n ₂ ) be a target image. _{Here, n 1} = −M ₁ , ···, M ₁ on the discrete space, N ₁ = 2M ₁ + 1 (M ₁ is a positive integer), and the two-dimensional discrete of _{f (n 1} , n _2). Assuming that the calculation result of the Fourier transform (discrete Fourier Transform: hereinafter, DFT) is F (k ₁ , k ₂ ), F (k ₁ , k ₂ ) is expressed by the equation (1).

In equation (1), _AF (k ₁ , k ₂ ) is the amplitude component of f (n ₁ , n ₂ ^{), and e jθF} (k 1, k 2) is the phase component of f (n ₁ , n _2). be.

Similarly, in a discrete space, n ₂ = -M ₂ , ..., M ₂ , N ₂ = 2 M ₂ + 1 (M ₂ is a positive integer), and g (n ₁ , n ₂ ) two-dimensional DFT. Assuming that the calculation result of is G (k ₁ , k ₂ ), G (k ₁ , k ₂ ) is expressed as in Eq. (2).

In equation (2), _AG (k ₁ , k ₂ ) is the amplitude component of g (n ₁ , n ₂ ^{), and e jθG} (k 1, k 2) is the phase component of g (n ₁ , n _2). be.

The phase-limited synthesis function used in the phase-limited synthesis processing is defined as in equation (3) using equations (1) and (2).

The phase-limited correlation function according to the embodiment is as shown in the equation (4) by applying a two-dimensional inverse discrete Fourier transform (hereinafter, IDFT) to the phase-limited composite function of the equation (3). expressed.

The 2-dimensional images _s c of the continuous space is defined _(x 1, _{x 2),} by a minute amount of movement [delta] ₁ in _{x 1} direction and the image obtained by shifting the _{x 2} direction by a minute amount of movement [delta] ₂ is is expressed as _{s c (x 1 -δ 1,} x 2 -δ 2). The two-dimensional image f (n ₁ , n ₂ ) on the discrete space sampled at the sampling interval T ₁ is defined by Eq. (5).

Similarly, the two-dimensional image g (n ₁ , n _{2 ) on the discrete space sampled at the sampling interval T 2} is defined as in Eq. (6).

In equations (5) and (6), n ₁ = -M ₁ , ..., M ₁ and n ₂ = -M ₂ , ..., M ₂ . As a result, the phase-limited correlation function for the two-dimensional images f (n ₁ , n ₂ ) and g (n ₁ , n ₂ ) in the discrete space is expressed in the general form as in Eq. (7). In equation (7), α = 1.

As shown in FIG. 6, the rotational movement amount calculation unit 241 includes a first conversion processing unit 301, a logarithmic conversion processing unit 302, a polar coordinate conversion unit 303, a second conversion processing unit 304, and a first phase limited synthesis unit 305. And the first inverse conversion processing unit 306.

The first conversion processing unit 301 performs two-dimensional DFT processing on the base image. In addition, the first conversion processing unit 301 performs two-dimensional DFT processing on the target image. The two-dimensional DFT process performed by the first conversion processing unit 301 includes a two-dimensional DFT and a known shift process for shifting the quadrant with respect to the calculation result of the two-dimensional DFT. Hereinafter, this shift process may be referred to as "shift". The two-dimensional DFT performed by the first conversion processing unit 301 may be a two-dimensional FFT.

The logarithmic conversion unit 302 performs logarithmic conversion on the calculation result of the first conversion processing unit 301 for the base image. Further, the logarithmic conversion unit 302 performs logarithmic conversion on the calculation result of the first conversion processing unit 301 for the target image. The logarithmic conversion by the logarithmic conversion unit 302 has the effect of compressing the amplitude spectrum that tends to be concentrated in the low frequency region of the spatial frequency in the natural image.

The polar coordinate conversion unit 303 performs polar coordinate conversion on the calculation result of the logarithmic conversion unit 302 for the base image. Further, the polar coordinate conversion unit 303 performs polar coordinate conversion on the calculation result of the logarithmic conversion unit 302 for the target image. When the logarithmic conversion by the logarithmic conversion unit 302 is not performed, the polar coordinate conversion unit 303 performs polar coordinate conversion on the calculation result by the first conversion processing unit 301 for the base image, and the first conversion processing unit 301 for the target image. Perform polar coordinate transformation on the calculation result by. Polar conversion by polar coordinate transformation unit 303 is a process of converting the movement amount of the rotational direction to the amount of movement of the parallel direction (n ₁ direction and n ₂ direction) in the formula (1) to (7).

As shown in the equation (1), the second conversion processing unit 304 performs two-dimensional DFT processing (two-dimensional DFT + shift) on the calculation result of the polar coordinate conversion unit 303 for the base image. The processing result of the base image by the second conversion processing unit 304 is stored in advance in, for example, the storage unit 212 as base POC data normalized by the amplitude component prior to the arithmetic processing by the first phase limiting synthesis unit 305. Will be done. Further, as shown in the equation (2), the second conversion processing unit 304 performs two-dimensional DFT processing (two-dimensional DFT + shift) on the calculation result of the polar coordinate conversion unit 303 for the target image. The two-dimensional DFT performed by the second conversion processing unit 304 may also be a two-dimensional FFT.

As shown in the equation (3), the first phase limited synthesis unit 305 is based on the base POC data (first data) obtained in advance for the base image and the calculation result by the second conversion processing unit 304 for the target image. A phase-limited synthesis process is performed to synthesize the target POC data (second data) normalized by the amplitude component.

The first inverse transformation processing unit 306 performs two-dimensional IDFT processing on the calculation result by the first phase limited synthesis unit 305. The two-dimensional IDFT process performed by the first inverse transformation processing unit 306 includes a two-dimensional IDFT and a known shift process for shifting the quadrant with respect to the calculation result of the two-dimensional IDFT. The two-dimensional IDFT may be calculated by a two-dimensional inverse Fourier transform (hereinafter, IFFT).

The rotational movement amount calculation unit 241 calculates the rotational movement amount and the rotational movement direction based on the calculation result by the first inverse conversion processing unit 306. Specifically, the rotational movement amount calculation unit 241 obtains the rotational movement amount and the rotational movement direction at the pixel level by specifying the peak position based on the calculation result by the first inverse transformation processing unit 306. After that, the rotation movement amount calculation unit 241 specifies the pixel position when the correlation value of the phase-limited correlation function shown in the equation (7) becomes maximum in the vicinity of the peak position specified at the pixel level, thereby substituting. Obtain the amount of rotational movement and the direction of rotational movement at the pixel level.

The rotational movement amount calculation unit 241 does not have to calculate the rotational movement amount and the rotational movement direction by the phase limitation correlation processing, and may calculate the rotational movement amount and the rotational movement direction by a known method.

The translation amount calculation unit 243 calculates the translation amount and the translation direction between the base image and the target image aligned by the alignment processing unit 242, which will be described later. The translation amount calculation unit 243 performs translational movement amount and parallelism between the base image and the target image by performing phase-limited correlation processing on the base image and the target image aligned by the alignment processing unit 242. Calculate the moving direction. Such phase-limited correlation processing is the same as the processing disclosed in Japanese Patent Application Laid-Open No. 2015-043898.

The translation amount calculation unit 243 obtains the translation amount and the translation direction between the base image and the target image aligned by the alignment processing unit 242. Specifically, the translation amount calculation unit 243 performs phase-limited correlation processing on the base image and the target image aligned by the alignment processing unit 242, thereby between the base image and the target image. Calculate the amount of translation and the direction of translation.

As shown in FIG. 7, the translation amount calculation unit 243 includes a third conversion processing unit 311, a second phase limited synthesis unit 312, and a second inverse conversion processing unit 313.

As shown in the equation (1), the third conversion processing unit 311 performs two-dimensional DFT processing (two-dimensional DFT + shift) on the base image. The processing result of the base image by the third conversion processing unit 311 is, for example, a storage unit as the base POC data (third data) normalized by the amplitude component prior to the arithmetic processing by the second phase limited synthesis unit 312. Pre-stored in 212. Further, the third conversion processing unit 311 performs two-dimensional DFT processing (two-dimensional DFT + shift) on the target image as shown in the equation (2). The two-dimensional DFT performed by the third conversion processing unit 311 may be a two-dimensional FFT.

As shown in the equation (3), the second phase limited synthesis unit 312 is based on the base POC data (third data) obtained in advance for the base image and the calculation result by the third conversion processing unit 311 for the target image. Then, a phase-limited synthesis process for synthesizing the target POC data (fourth data) normalized by the amplitude component is performed.

The second inverse transformation processing unit 313 performs two-dimensional IDFT processing (two-dimensional IDFT + shift) on the calculation result by the second phase limited synthesis unit 312. The two-dimensional IDFT performed by the second inverse transform processing unit 313 may be a two-dimensional IFFT.

The translation amount calculation unit 243 calculates the translation amount and the translation direction based on the calculation result by the second inverse transformation processing unit 313. Specifically, the translation amount calculation unit 243 obtains the translation amount and the translation direction at the pixel level by specifying the peak position based on the calculation result by the second inverse transformation processing unit 313. After that, the translation amount calculation unit 243 specifies the pixel position when the correlation value of the phase-limited correlation function shown in Eq. (7) becomes maximum in the vicinity of the peak position specified at the pixel level, thereby substituting. Find the translation amount and translation direction at the pixel level.

The alignment processing unit 242 aligns the base image and the target image in the rotation direction based on the rotation movement amount and the rotation movement direction obtained by the rotation movement amount calculation unit 241. Specifically, the alignment processing unit 242 aligns the target image with respect to the rotation direction based on the rotation movement amount and the rotation movement direction calculated by the rotation movement amount calculation unit 241. .. The alignment processing unit 242 aligns the base image with respect to the rotation direction based on the rotation movement amount and the rotation movement direction calculated by the rotation movement amount calculation unit 241. May be good.

The data processing unit 230 that functions as described above includes, for example, a microprocessor, RAM, ROM, a hard disk drive, a circuit board, and the like. A computer program that causes a microprocessor to execute the above functions is stored in a storage device such as a hard disk drive in advance.

(User interface)
The user interface 240 includes a display unit 240A and an operation unit 240B. The display unit 240A includes the display device and the display device 3 of the arithmetic control unit 200 described above. The operation unit 240B includes the operation device of the arithmetic control unit 200 described above. The operation unit 240B may include various buttons and keys provided on the housing of the ophthalmic apparatus 1 and on the outside. Further, the display unit 240A may include various display devices such as a touch panel provided on the housing of the fundus camera unit 2.

The display unit 240A and the operation unit 240B do not need to be configured as separate devices. For example, it is possible to use a device such as a touch panel in which a display function and an operation function are integrated. In that case, the operation unit 240B includes the touch panel and a computer. The operation content for the operation unit 240B is input to the control unit 210 as an electric signal. Further, the graphical user interface (GUI) displayed on the display unit 240A and the operation unit 240B may be used to perform operations and information input.

The optical system shown in FIG. 1 (for example, the interference optical system included in the OCT unit 100) is an example of the “optical system” according to the embodiment. The photographing optical system 30 is an example of the “photographing unit” according to the embodiment. The optical system drive unit 1A is an example of the “moving mechanism” according to the embodiment. The alignment optical system 50 is an example of the “bright spot projection system” according to the embodiment. The base image is an example of the "first image" or "third image" according to the embodiment, and the target image is an example of the "second image" or "fourth image" according to the embodiment. The rotation movement amount calculation unit 241 is an example of the "first rotation movement amount calculation unit" or the "second rotation movement amount calculation unit" according to the embodiment. The alignment processing unit 242 is an example of the "first alignment processing unit" or the "second alignment processing unit" according to the embodiment. The translation amount calculation unit 243 is an example of the "first translation amount calculation unit" or the "second translation amount calculation unit" according to the embodiment.

[Operation example]
An operation example of the ophthalmic apparatus according to the embodiment will be described.

FIG. 8 shows a flow chart showing an example of the operation of the ophthalmic apparatus 1 according to the embodiment. In FIG. 8, it is assumed that the front lens 23 is arranged between the eye E to be inspected and the objective lens 22.

(S1: Start photographing the anterior segment)
First, acquisition of a near-infrared moving image of the anterior segment is started by continuously illuminating the anterior segment with illumination light from the observation light source 11 (which becomes near-infrared light by the visible cut filter 14). This near-infrared moving image is obtained in real time until the end of continuous illumination. The image of each frame constituting this moving image is temporarily stored in the frame memory (storage unit 212) and sequentially sent to the data processing unit 230.

An alignment target by the alignment optical system 50 and a split target by the focus optical system 60 are projected on the eye E to be inspected. Therefore, the alignment optotype and the split optotype are drawn on the near-infrared moving image. Alignment and focusing can be performed using these optotypes. In addition, a fixation target by LCD 39 is also projected on the eye E to be inspected. The subject is instructed to stare at this fixation target.

(S2: Alignment)
The data processing unit 230 sequentially analyzes the frames obtained by photographing the eye E to be inspected as a moving image by the optical system, obtains the position of the alignment optotype, and calculates the amount of movement of the optical system. The control unit 210 performs auto-alignment by controlling the optical system drive unit 1A based on the movement amount of the optical system calculated by the data processing unit 230.

(S3: Focusing)
The data processing unit 230 sequentially analyzes the frames obtained by photographing the eye E to be inspected as a moving image by the optical system, obtains the position of the split optotype, and the amount of movement of the photographing focusing lens 31 and the OCT focusing lens 43. Is calculated. The control unit 210 performs autofocus by controlling the focusing drive units 31A and 43A based on the amount of movement of the photographing focusing lens 31 and the OCT focusing lens 43 calculated by the data processing unit 230.

(S4: Start tracking)
Subsequently, the control unit 210 starts auto-tracking. Specifically, the data processing unit 230 monitors the movement (change in position) of the eye E to be inspected E by analyzing the frames sequentially obtained by photographing the eye E to be inspected as a moving image in real time by the optical system. The control unit 210 controls the optical system drive unit 1A so as to move the optical system according to the position of the eye E to be inspected, which is sequentially acquired. As a result, the optical system can be made to follow the movement of the eye E to be inspected in real time, and it is possible to maintain a suitable positional relationship in which alignment and focus are in focus.

(S5: Set scanning area)
The control unit 210 causes the display unit 240A to display a near-infrared moving image in real time. The user sets a scanning region on the near-infrared moving image by using the operation unit 240B. The scanning area to be set may be a one-dimensional area or a two-dimensional area.

(S6: OCT measurement)
The control unit 210 controls the light source unit 101 and the optical path length changing unit 41, and controls the optical scanner 42 based on the scanning region set in step S5 to perform OCT measurement of the anterior segment of the eye. The image forming unit 220 forms a tomographic image of the anterior segment based on the obtained detection signal. When the scanning mode is a three-dimensional scan, the data processing unit 230 forms a three-dimensional image of the anterior segment of the eye based on a plurality of tomographic images formed by the image forming unit 220. This is the end of this operation example (end).

FIG. 9 shows a flow chart of a processing example of step S4 of FIG.

(S100: Measure the fundus?)
The control unit 210 determines whether or not the measurement site (photographing site) is the fundus. For example, a detection unit for detecting whether or not the front lens 23 is arranged between the eye E to be inspected and the objective lens 22 is provided, and the control unit 210 measures based on the detection result obtained by the detection unit. It is possible to determine whether or not the site is the fundus. Such a detection unit is turned on when the front lens 23 is arranged between the eye E to be inspected and the objective lens 22, and the front lens 23 is retracted from between the eye E to be inspected and the objective lens 22. It can include a microswitch that sometimes turns off.

When it is determined that the measurement site is the fundus (S100: Y), the operation of the ophthalmic apparatus 1 shifts to step S101. When it is determined that the measurement site is not the fundus (S100: N), the operation of the ophthalmic apparatus 1 shifts to step S102.

(S101: fundus mode)
When it is determined in step S100 that the measurement site is the fundus (S100: Y), the control unit 210 executes tracking control in the fundus mode. That is, the data processing unit 230 sequentially calculates the amount of sub-pixel level misalignment between the base image and the target image, and the control unit 210 is calculated by the data processing unit 230 for each one or a plurality of frames. The optical system is moved so as to correct the amount of misalignment.

(S102: anterior segment mode)
When it is determined in step S100 that the measurement site is not the fundus (S100: N), the control unit 210 executes tracking control in the anterior ocular region mode. That is, the analysis unit 231 obtains the displacement of the feature region and the bright spot image with respect to the reference position in the anterior segment image, and the control unit 210 cancels the displacement obtained by the analysis unit 231 for each one or a plurality of frames. The optical system is moved so as to. Further, the analysis unit 231 obtains the three-dimensional position of the eye E to be inspected as described above, and the control unit 210 obtains the optical system for each one or a plurality of frames based on the three-dimensional position obtained by the analysis unit 231. You may move it.

(S103: Finished?)
Following step S101 or step S102, the control unit 210 determines whether or not to end the tracking. When it is determined to end the tracking (S103: Y), the tracking control of the ophthalmic apparatus 1 ends (end). When it is determined that the tracking is not completed (S103: N), the operation of the ophthalmic apparatus 1 shifts to step S100.

In the anterior segment mode, the control unit 210 can maintain the positional relationship between the eye E to be inspected and the device optical system based on the displacement of the feature region and the bright spot image with respect to the reference position in the anterior segment image. May be determined. When it is determined that the positional relationship cannot be maintained, the data processing unit 230 sequentially calculates the amount of sub-pixel level misalignment between the corresponding partial image and the partial image, and the control unit 210 sequentially calculates 1. Alternatively, the optical system is moved so as to correct the amount of misalignment calculated by the data processing unit 230 for each of a plurality of frames. In this case, the rotation movement amount calculation unit 241 calculates the first rotation movement amount between the partial image in the target image and the corresponding partial image corresponding to the partial image in the base image. The alignment processing unit 242 aligns the corresponding partial image and the partial image in the rotation direction based on the first rotational movement amount. The translation amount calculation unit 243 performs phase-limited correlation processing on the corresponding partial image and the partial image aligned by the alignment processing unit 242, whereby the first interposition between the corresponding partial image and the partial image is performed. Calculate the amount of translation. The control unit 210 controls the optical system drive unit 1A based on the first translation amount.

Further, in the fundus mode, the control unit 210 determines whether or not the positional relationship between the eye E to be inspected and the device optical system can be maintained based on the rotational movement amount and the parallel movement amount obtained by the phase limitation correlation processing. You may. When it is determined that the positional relationship cannot be maintained, the analysis unit 231 obtains the displacement of the feature region in the base image and the target image, and the control unit 210 obtains the displacement of the optical system drive unit 1A based on the obtained displacement. To control.

Hereinafter, an example of tracking control processing using phase-limited correlation processing will be described. Hereinafter, an example of tracking control processing in the fundus mode will be mainly described, but the same applies to the tracking control processing in the anterior segment mode.

FIG. 10 shows a flow chart of a processing example for tracking control in the fundus mode according to the embodiment. For example, when the eye E to be inspected is changed or the photographing mode is changed, the process shown in FIG. 10 is executed.
(S11: Initial setting)
First, the main control unit 211 performs a predetermined initialization process. The initialization process includes securing resources, setting a scan area for acquiring a base image and a target image, and initializing the data processing unit 230.

(S12: Base image processing)
When the user instructs the start of tracking, the control unit 210 performs base image processing for performing phase-limited correlation processing on the base image. Details of the base image processing will be described later.

(S13: Target image processing)
The control unit 210 performs target image processing for performing phase-limited correlation processing on sequentially input target images. Details of the target image processing will be described later.

(S14: Shooting finished?)
When the eye to be imaged changes, the result of the base image processing performed in step S12 becomes unnecessary. Therefore, the control unit 210 determines whether or not the imaging of the eye to be inspected E, which is the target of tracking, has been completed. The control unit 210 can determine whether or not the imaging of the eye E to be inspected is completed based on, for example, the operation content of the user via the operation unit 240B. When it is determined that the imaging of the eye to be inspected E is not completed (S14: N), the operation of the ophthalmic apparatus 1 shifts to step S13. When it is determined that the imaging of the eye E to be inspected is completed (S14: Y), the operation of the ophthalmic apparatus 1 shifts to step S15.

(S15: Next shooting?)
Subsequently, when taking a picture for another eye to be inspected, it is necessary to re-execute the base image processing. Therefore, the control unit 210 determines whether or not the next eye to be inspected is photographed. When it is determined that the next imaging is not performed (S15: N), the operation of the ophthalmic apparatus 1 ends (end). When it is determined that the next imaging is performed (S15: Y), the operation of the ophthalmic apparatus 1 shifts to step S12.

Next, the base image processing in step S12 will be described.

FIG. 11 shows an example of the flow of base image processing according to the embodiment.

(S21: Apodization processing)
First, the rotation movement amount calculation unit 241 performs apodization processing on the base image (corresponding partial image in the anterior segment mode, the same applies hereinafter). The apodization process is a process of increasing the dynamic range by reducing the amplitude of the side lobes while suppressing the decrease in the amplitude of the main lobe to some extent by multiplying the apodization function. As the apodization function, there are known window functions such as a Hanning window, a Gaussian window, and a rectangular window. The apodization process is performed by, for example, an apodization process unit (not shown) in the first conversion process unit 301 or the rotational movement amount calculation unit 241.

(S22: 2D DFT)
Next, the first conversion processing unit 301 applies a two-dimensional DFT to the result of the apodization processing on the base image in step S21.

(S23: Logarithmic transformation)
Next, the logarithmic conversion unit 302 performs logarithmic conversion on the processing result of the two-dimensional DFT in step S22. The logarithmic transformation is expressed by the equation (8), where Re is the real component of the processing result of the two-dimensional DFT, Im is the imaginary component, and Am is the logarithmic transformation result. This compresses the amplitude spectrum, which tends to be concentrated in the low frequency region of the spatial frequency in the natural image.

(S24: Log-Polar conversion)
Next, the polar coordinate conversion unit 303 performs Log-Polar conversion on the processing result of the logarithmic conversion in step S23. As a result, the radial direction is converted to the x direction and the declination direction is converted to the y direction.

(S25: 2D DFT)
Next, the second conversion processing unit 304 applies a two-dimensional DFT to the processing result of the Log-Polar transform in step S24.

(S26: Save POC data)
Next, the rotation movement amount calculation unit 241 normalizes with an amplitude component based on the processing result of the two-dimensional DFT in step S25, and stores it in the storage unit 212 as the first base POC data based on the processing result of the two-dimensional DFT. Here, the first base POC data stored in the storage unit 212 is used for calculating the correlation value of the phase-limited correlation function for calculating the rotational movement amount and the rotational direction.

(S27: Apodization process)
Subsequently, the translation amount calculation unit 243 generates base POC data to be used for calculating the correlation value of the phase-limited correlation function for calculating the translation amount and the translation direction with respect to the base image. Therefore, the translation amount calculation unit 243 performs apodization processing on the base image. This apodization process is the same process as in step S21. When the processing result of step S21 is stored in the storage unit 212, the processing of step S27 can be omitted.

(S28: 2D DFT)
Next, the third conversion processing unit 311 applies a two-dimensional DFT to the real number component as a result of the apodization processing on the base image.

(S29: Save POC data)
Next, the translation amount calculation unit 243 normalizes with an amplitude component based on the processing result of the two-dimensional DFT in step S28, and stores the second base POC data based on the processing result of the two-dimensional DFT in the storage unit 212. Here, the second base POC data stored in the storage unit 212 is used for calculating the correlation value of the phase-limited correlation function for calculating the translation amount and the translation direction. This completes the series of base image processing (end).

Next, the target image processing in step S13 will be described.

12 to 14 show an example of the flow of target image processing according to the embodiment. The target image processing includes processing for generating target POC data for the target image (partial image in the anterior segment mode, the same applies hereinafter), calculation processing for the amount of rotational movement and the direction of rotational movement, alignment processing, and translation. Includes processing for calculating quantity and translation direction.

(S41: Apodization processing)
First, the rotation movement amount calculation unit 241 performs apodization processing on the target image. This processing is the same as in step S21, and is performed by an apodization processing unit (not shown) in the first conversion processing unit 301 or the rotational movement amount calculation unit 241.

(S42: 2D DFT)
Next, the first conversion processing unit 301 applies a two-dimensional DFT to the result of the apodization processing on the target image in step S41.

(S43: Logarithmic transformation)
Next, the logarithmic conversion unit 302 performs logarithmic conversion on the processing result of the two-dimensional DFT in step S42. This logarithmic conversion is the same as in step S23.

(S44: Log-Polar conversion)
Next, the polar coordinate conversion unit 303 performs a Log-Polar transformation on the processing result of the logarithmic transformation in step S43. This Log-Polar transformation is the same as in step S24.

(S45: 2D DFT)
Next, the second conversion processing unit 304 applies a two-dimensional DFT to the processing result of the Log-Polar transform in step S44.

(S46: Phase-limited synthesis processing)
Next, the first phase limited synthesis unit 305 combines the first base POC data stored in the storage unit 212 in step S26 and the target POC data obtained by normalizing the processing result of the two-dimensional DFT in step S45 with an amplitude component. The phase-limited synthesis process is performed according to the equation shown in the equation (3). Here, the first base POC data is the base POC data generated for the target image.

(S47: 2D IDFT)
Next, the first inverse transformation processing unit 306 applies a two-dimensional IDFT to the processing result of the phase-limited synthesis processing in step S46 according to the equation shown in the equation (4).

(S48: Specify the peak position)
By specifying the peak position from the processing result of step S47, the radius (coordinates in the x direction) and the declination (coordinates in the y direction) having high correlation values are specified at the pixel level. Therefore, the rotation movement amount calculation unit 241 obtains the peak value of the processing result of step S47, acquires the address of the peak position corresponding to the peak value, and stores it in the storage unit 212.

(S49: rotation angle ≤ TH1?)
The rotation movement amount calculation unit 241 determines whether or not the rotation angle (absolute value) corresponding to the declination is equal to or less than the threshold value TH1 based on the address of the peak position stored in the storage unit 212. When it is determined that the rotation angle is not equal to or less than the threshold value TH1 (S49: N), the rotation movement amount calculation unit 241 determines that an error occurs and ends a series of processing (end). On the other hand, when it is determined that the rotation angle is equal to or less than the threshold value TH1 (S49: Y), the process of the rotation movement amount calculation unit 241 shifts to step S50.

(S50: Specify the peak position at the sub-pixel level)
When it is determined that the rotation angle is equal to or less than the threshold value TH1 (S49: Y), the rotation movement amount calculation unit 241 calculates the correlation value of the phase-limited correlation function at the sub-pixel level according to the equation (7). Specifically, as disclosed in Japanese Patent Application Laid-Open No. 2015-043898, the rotational movement amount calculation unit 241 obtains a plurality of correlation values of the phase-limited correlation function shown in the equation (7) at the subpixel level. By specifying the peak position, the declination (coordinates in the y direction) having a high correlation value is specified. The rotation movement amount calculation unit 241 acquires an address corresponding to the specified peak value and stores it in the storage unit 212.

(S51: Calculate Δθ)
Next, the rotational movement amount calculation unit 241 calculates the rotational movement amount Δθ corresponding to the peak position specified at the sub-pixel level, as disclosed in Japanese Patent Application Laid-Open No. 2015-043898. The direction of rotational movement is specified by the sign of Δθ.

(S52: Alignment)
When the rotational movement amount Δθ is calculated, the alignment processing unit 242 rotates the target image stored in the storage unit 212 by −Δθ.

(S53: Apodization processing)
Subsequently, the translation amount calculation unit 243 calculates the translation amount and the translation direction. That is, the translation amount calculation unit 243 performs apodization processing on the target image aligned in step S52. This processing is performed, for example, by an apodization processing unit (not shown) in the third conversion processing unit 311 or the translation amount calculation unit 243.

(S54: 2D DFT)
Next, the third conversion processing unit 311 applies a two-dimensional DFT to the result of the apodization processing on the target image in step S53.

(S55: Phase-limited synthesis processing)
Next, the second phase limited synthesis unit 312 selects the second base POC data stored in the storage unit 212 in step S29 and the target POC data obtained by normalizing the processing result of the two-dimensional DFT in step S54 with an amplitude component. The phase-limited synthesis process is performed according to the equation shown in the equation (3).

(S56: 2D IDFT)
Next, the second inverse transformation processing unit 313 applies a two-dimensional IDFT to the processing result of the phase-limited synthesis processing according to the equation shown in the equation (4).

(S57: Specify the peak position)
By specifying the peak position from the processing result of step S59, the coordinates in the x direction and the coordinates in the y direction of the correlation value are specified. The translation amount calculation unit 243 obtains the peak value of the processing result in step S59, acquires the address of the peak position corresponding to the peak value, and stores it in the storage unit 212.

(S58: Movement amount ≤ TH2?)
Based on the address of the peak position stored in the storage unit 212, the translation amount calculation unit 243 determines whether or not, for example, the movement amount (absolute value) in the x direction and the movement amount (absolute value) in the y direction are equal to or less than the threshold value TH2. To determine. When it is determined that the movement amount in the x direction and the movement amount in the y direction are not equal to or less than the threshold value TH2 (S58: N), the translation amount calculation unit 243 determines that an error occurs and ends a series of processing (end). .. On the other hand, when it is determined that the movement amount in the x direction and the movement amount in the y direction are equal to or less than the threshold value TH2 (S58: Y), the processing of the parallel movement amount calculation unit 243 shifts to S59.

(S59: Specify the peak position at the sub-pixel level)
When it is determined that the movement amount in the x direction and the movement amount in the y direction are equal to or less than the threshold value TH2 (S58: Y), the translation amount calculation unit 243 of the translation amount calculation unit 243 of the phase-limited correlation function at the subpixel level according to the equation (7). Calculate the correlation value. Specifically, the translation amount calculation unit 243 obtains a plurality of correlation values of the phase-limited correlation function shown in the equation (7) at the sub-pixel level, as disclosed in Japanese Patent Application Laid-Open No. 2015-043898. By specifying the peak position, the amount of movement with a high correlation value (coordinates in the x direction and coordinates in the y direction) is specified. The translation amount calculation unit 243 acquires an address corresponding to the specified peak value and stores it in the storage unit 212.

(S60: Calculate Δx and Δy)
Next, the translation amount calculation unit 243 calculates the translation amounts Δx and Δy corresponding to the peak positions specified at the sub-pixel level, as disclosed in Japanese Patent Application Laid-Open No. 2015-043898. The translation direction is specified by the signs of Δx and Δy. This completes the series of target image processing (end).

The rotational movement amount Δθ and the rotational movement direction calculated as described above, and the parallel movement amounts Δx, Δy and the parallel movement direction are output to the control unit 210. The control unit 210 (main control unit 211) controls the optical system drive unit 1A based on the calculated translation amounts Δx and Δy to move the device optical system three-dimensionally for tracking. .. The control unit 210 may control the optical system drive unit 1A based on the rotational movement amount Δθ and the rotational movement direction.

[effect]
The ophthalmic apparatus according to the embodiment will be described.

The ophthalmic apparatus (1) according to the embodiment includes an optical system (the optical system shown in FIG. 1, an interference optical system included in the OCT unit 100), an imaging unit (imaging optical system 30), and a moving mechanism (optical system driving unit). 1A) and a control unit (210, main control unit 211) are included. The optical system is used to collect data on the anterior segment or fundus (Ef) of the eye to be inspected (E). The photographing unit photographs the anterior segment of the eye or the fundus. The moving mechanism moves the eye to be inspected and the optical system relative to each other. The control unit is a moving mechanism that maintains the positional relationship between the eye to be inspected and the optical system based on the anterior segment image obtained by the imaging unit when the optical system is in the anterior segment mode in which data of the anterior segment is collected. The movement mechanism is controlled so as to maintain the positional relationship based on the fundus image obtained by the photographing unit when the optical system is in the fundus mode in which the data of the fundus is collected.

According to such a configuration, since the tracking control corresponding to the data collection site of the eye to be inspected is performed, the tracking can be suitably performed according to the measurement site. For example, by using phase-limited correlation processing to track the fundus and determining the displacement using another method for tracking the anterior segment, highly accurate tracking of the fundus and the anterior segment of the eye can be achieved. It will be possible to provide an ophthalmic apparatus capable of both tracking and tracking.

Further, the ophthalmic apparatus according to the embodiment includes an analysis unit (231) for specifying a characteristic region in the anterior segment image, and in the anterior segment mode, the control unit is a feature region for a reference position in the anterior segment image. The movement mechanism may be controlled based on the displacement.

According to such a configuration, tracking of the anterior segment of the eye is performed based on the displacement of the characteristic region in the image of the anterior segment of the eye. Can be provided.

Further, the ophthalmic apparatus according to the embodiment identifies a bright spot projection system (alignment optical system 50) that projects bright spots on the eye to be inspected and a bright spot image based on the bright spots in the part image acquired by the photographing unit. In the anterior segment mode, the control unit may control the movement mechanism based on the displacement of the bright spot image with respect to the reference position in the anterior segment image.

According to such a configuration, tracking of the anterior segment of the eye is performed based on the displacement of the bright spot image in the image of the anterior segment of the eye. Equipment can be provided.

Further, in the ophthalmic apparatus according to the embodiment, the imaging unit includes two or more optometry cameras that photograph the anterior segment from different directions substantially simultaneously, and two or more images obtained substantially simultaneously by the imaging unit. Including the analysis unit (231) that obtains the three-dimensional position of the eye to be inspected by analyzing the image of the anterior eye, the control unit is the above-mentioned three-dimensional position with respect to the reference position corresponding to the eye to be inspected in the anterior eye mode. The movement mechanism may be controlled based on the displacement of the eye to be moved relative to the eye to be inspected and the optical system in three dimensions.

According to such a configuration, tracking of the anterior segment of the eye is performed based on the displacement of the three-dimensional position in the image of the anterior segment of the eye. Equipment can be provided.

Further, in the ophthalmic apparatus according to the embodiment, the photographing unit acquires the first image (base image) and the second image (target image) at different timings, and the partial image in the second image and the partial image in the first image The first rotational movement amount calculation unit (rotational movement amount calculation unit 241) that calculates the first rotational movement amount between the corresponding partial image corresponding to the partial image, and the corresponding partial image and portion based on the first rotational movement amount. The phase of the first alignment processing unit (alignment processing unit 242) that aligns the image with the image in the rotational direction, and the corresponding partial image and the partial image that have been aligned by the first alignment processing unit. The anterior segment mode includes a first translation amount calculation unit (translation amount calculation unit 243) that calculates a first translation amount between the corresponding partial image and the partial image by performing limited correlation processing. At this time, the control unit determines whether or not the positional relationship can be maintained based on the displacement, and when it is determined that the positional relationship cannot be maintained, the control unit moves the movement mechanism based on the first translation amount. You may control it.

According to such a configuration, when it is determined that tracking of the anterior segment is impossible based on the above displacement, tracking of the anterior segment is performed by phase-limited correlation processing. It is possible to provide an ophthalmic apparatus capable of realizing tracking with high accuracy.

Further, in the ophthalmic apparatus according to the embodiment, the first rotation movement amount calculation unit may calculate the first rotation movement amount by performing phase-limited correlation processing on the corresponding partial image and the partial image.

With such a configuration, it is possible to align the corresponding partial image and the partial image based on the rotational movement amount calculated with high accuracy (for example, at the sub-pixel level), so that it is smaller. The amount of misalignment can be obtained, and even more accurate tracking becomes possible.

Further, in the ophthalmic apparatus according to the embodiment, the photographing unit acquires the third image (base image) and the fourth image (target image) of the fundus of the eye to be examined at different timings, and the third image and the fourth image. The position in the rotation direction between the second rotation movement amount calculation unit (rotational movement amount calculation unit 241) that calculates the second rotation movement amount between the two images and the three images and the four images based on the second rotation movement amount. By performing phase-limited correlation processing on the second alignment processing unit (alignment processing unit 242) that performs alignment and the third and fourth images that have been aligned by the second alignment processing unit. A second translation amount calculation unit (translation amount calculation unit 243) for calculating a second translation amount between the third image and the fourth image is included, and in the fundus mode, the control unit is a second. The movement mechanism may be controlled based on the amount of translation.

According to such a configuration, since the fundus is tracked by phase-limited correlation processing, it is possible to provide an ophthalmologic apparatus capable of highly accurate tracking of the fundus while enabling tracking of the anterior segment of the eye. can.

Further, in the ophthalmic apparatus according to the embodiment, the analysis unit identifies the feature regions in the third image and the fourth image acquired by the imaging unit, and the control unit determines the second rotational movement amount and the second translation amount. Based on this, it is determined whether or not the positional relationship can be maintained, and when it is determined that the positional relationship cannot be maintained, the movement mechanism is controlled based on the displacement of the feature regions in the third and fourth images. You may.

According to such a configuration, when it is determined that the fundus tracking using the phase-limited correlation processing is impossible, the fundus is tracked based on the displacement of the feature region in the fundus image. Therefore, the fundus tracking is performed. It is possible to provide an ophthalmologic device that can reliably perform the above.

Further, the ophthalmic apparatus (1) according to the embodiment includes an optical system (the optical system shown in FIG. 1, an interference optical system included in the OCT unit 100), an imaging unit (imaging optical system 30), and a moving mechanism (optical system). The drive unit 1A) and the control unit (210, main control unit 211) are included. The optical system is used to collect data for multiple sites of the eye to be inspected (E). The photographing unit photographs one of a plurality of parts. The moving mechanism moves the eye to be inspected and the optical system relative to each other. The control unit controls the movement mechanism so as to maintain the positional relationship between the eye to be inspected and the optical system based on the image of the collection site according to the data collection site by the optical system obtained by the imaging unit.

According to such a configuration, tracking control corresponding to the data collection site of the eye to be inspected is performed, so that it is possible to provide an ophthalmic apparatus capable of highly reproducible data collection with optimal tracking for the measurement site. can.

<Modification example>
The embodiments shown above are merely examples for carrying out the present invention. A person who intends to carry out the present invention can make arbitrary modifications, omissions, additions, etc. within the scope of the gist of the present invention.

In the above-described embodiment, the case where the configuration of the optical system is the configuration shown in FIG. 1 has been described, but the configuration of the optical system according to the embodiment is not limited to this. The optical system according to the embodiment may include an optical system for irradiating a treatment site on the fundus with laser light, an optical system for moving an optotype while the eye to be inspected is fixed, and the like.

In the above-described embodiment, the case where the imaging site is the fundus or the anterior segment of the eye has been described, but the imaging site is not limited to the fundus or the anterior segment of the eye. In addition, the imaging region may be three or more regions.

1 Ophthalmic apparatus 1A Optical system drive unit 10 Illumination optical system 23 Front lens 30 Imaging optical system 35 CCD image sensor 100 OCT unit 210 Control unit 211 Main control unit 212 Storage unit 220 Image formation unit 230 Data processing unit 231 Analysis unit 241 Rotation Movement amount calculation unit 242 Alignment processing unit 243 Parallel movement amount calculation unit E Eye to be inspected

Claims (5)

An optical system for collecting data on the anterior segment or fundus of the eye to be inspected,
An imaging unit that acquires a fundus image of the fundus, or a first image and a second image of the anterior segment at different timings.
A moving mechanism that relatively moves the eye to be inspected and the optical system,
An analysis unit that identifies a feature region in the image of the anterior segment of the eye,
When the optical system is in the anterior segment mode for collecting data of the anterior segment, the eye to be inspected and the optical system are based on the displacement of the characteristic region with respect to the reference position in the anterior segment image obtained by the imaging unit. Tracking is performed by controlling the movement mechanism so as to maintain the positional relationship of the eye fundus, and the positional relationship is based on the fundus image obtained by the photographing unit when the optical system is in the fundus mode for collecting the data of the fundus. A control unit that performs tracking by controlling the movement mechanism so as to maintain
A first rotation movement amount calculation unit that calculates a first rotation movement amount between the partial image in the second image and the corresponding partial image corresponding to the partial image in the first image.
A first alignment processing unit that aligns the corresponding partial image and the partial image in the rotation direction based on the first rotational movement amount.
By performing phase-limited correlation processing on the corresponding partial image and the partial image aligned by the first alignment processing unit, a first translation between the corresponding partial image and the partial image is performed. The first translation amount calculation unit that calculates the amount,
Including
The analysis unit identifies an image of a region in the second image in which the amount of movement with respect to the first image is equal to or greater than the first threshold value as the partial image.
In the anterior segment mode, the control unit determines whether or not the positional relationship can be maintained based on the displacement, and when it is determined that the positional relationship cannot be maintained, the first. 1 An ophthalmic apparatus that controls the movement mechanism based on the amount of parallel movement. An optical system for collecting data on the anterior segment or fundus of the eye to be inspected,
An imaging unit that acquires a fundus image of the fundus, or a first image and a second image of the anterior segment at different timings.
A moving mechanism that relatively moves the eye to be inspected and the optical system,
An analysis unit that identifies a feature region in the image of the anterior segment of the eye,
When the optical system is in the anterior segment mode for collecting data of the anterior segment, the eye to be inspected and the optical system are based on the displacement of the characteristic region with respect to the reference position in the anterior segment image obtained by the imaging unit. Tracking is performed by controlling the movement mechanism so as to maintain the positional relationship of the eye fundus, and the positional relationship is based on the fundus image obtained by the photographing unit when the optical system is in the fundus mode for collecting the data of the fundus. A control unit that performs tracking by controlling the movement mechanism so as to maintain
A first rotation movement amount calculation unit that calculates a first rotation movement amount between the partial image in the second image and the corresponding partial image corresponding to the partial image in the first image.
A first alignment processing unit that aligns the corresponding partial image and the partial image in the rotation direction based on the first rotational movement amount.
By performing phase-limited correlation processing on the corresponding partial image and the partial image aligned by the first alignment processing unit, a first translation between the corresponding partial image and the partial image is performed. The first translation amount calculation unit that calculates the amount,
Including
The analysis unit specifies a region in the second image in which the amount of movement with respect to the first image is equal to or less than the second threshold value, and identifies an image in a region other than the specified region in the second image as the partial image. death,
In the anterior segment mode, the control unit determines whether or not the positional relationship can be maintained based on the displacement, and when it is determined that the positional relationship cannot be maintained, the first. 1 An ophthalmic apparatus that controls the movement mechanism based on the amount of parallel movement. Claim 1 or claim 2 characterized in that the first rotation movement amount calculation unit calculates the first rotation movement amount by performing phase-limited correlation processing on the corresponding partial image and the partial image. The ophthalmic apparatus described in. The photographing unit acquires the third image and the fourth image of the fundus of the eye to be inspected at different timings.
A second rotation movement amount calculation unit that calculates a second rotation movement amount between the third image and the fourth image, and a second rotation movement amount calculation unit.
A second alignment processing unit that aligns the third image and the fourth image in the rotation direction based on the second rotational movement amount.
By performing phase-limited correlation processing on the third image and the fourth image aligned by the second alignment processing unit, a second image between the third image and the fourth image is performed. The second translation amount calculation unit that calculates the parallel movement amount, and
Including
Wherein when the fundus mode, the control unit may ophthalmic apparatus according to any one of claims 1 to 3, wherein the controller controls the moving mechanism based on the second amount of translation. The analysis unit identifies the feature regions in the third image and the fourth image acquired by the photographing unit.
The control unit determines whether or not the positional relationship can be maintained based on the second rotational movement amount and the second parallel movement amount, and when it is determined that the positional relationship cannot be maintained. The ophthalmic apparatus according to claim 4 , wherein the movement mechanism is controlled based on the displacement of the feature region in the third image and the fourth image.

Images